三腔起搏器治疗心力衰竭疗效观察

目的探析三腔起搏器对心力衰竭患者的临床疗效。方法选取20例在我院接受三腔起搏器治疗的心力衰竭患者,对比治疗前后患者心功能相关指标。结果治疗后,患者各项心功能指标均得到改善(P<0.05)。结论三腔起搏器治疗心力衰竭患者的临床疗效显著。

ST—1型软式纤细双极心内膜起搏导管的研制与应用

心脏停搏是临床上经常遇到的一种危急症。目前,多采用心脏挤压和心腔内注射药物等措施进行抢救。但在设备条件较差的基层医院抢救成功率极低。因此,我们设想,在进行心内注药的同时,如能经心内穿刺针孔内送入一根纤细的起搏导管。

Idiopathic ventricular fibrillation with fragmented QRS complex and J wave in resting electrocardiogram

Objective To describe the clinical characteristics of idiopathic ventricular fibrillation （IVF） with fragmented QRS complex （f-QRS） and J wave in resting electrocardiogram. Methods We reviewed data from 21 case subjects in our hospital who were resuscitated after cardiac arrest due to IVF and assessed the prevalence of f-QRS and J wave in resting electrocardiogram （ECG）. All the case subjects were classified among three groups based on the electrocardiographic morphology： group I, both f-QRS and J wave were observed （n = 6）, group II, only J wave was observed （n = 9）, group III, neither f-QRS nor J wave was observed （n = 6）. Population characteristics, history of syncope or sudden cardiac arrest, incidence of ventricular fibrillation （VF）, and circumstance of VF were evaluated among the three groups. Results The incidence of index events （syncope, survived cardiac arrest and VF episodes recorded in implantable cardioverter defibrillator （ICD） or pacemakers） was 13.4 ~ 5.6 per-year in group I, 10.8 ~ 3.9 per-year in group II, and 9.8 -4- 4.2 per-year in group HI. There were significant differences in incidences among the three groups, the most frequent index events were observed in group I. The hazard ratio for incidence was 3.2 （95%CI, 1.1-7.9; P = 0.01）. The history and circumstance of the index events were different among the groups. In group I, all the index events occurred during sleep in early morning. In group II, four subjects suffered VF during strenuous physical activities or agitation state, two during sleep in early morning, three in usual activity. In group III, one subject suffered VF during sleep in early morning, one in agitation state, four in usual activity. Conclusions This study suggests that the IVF patients with the combined appearance of f-QRS and J wave in the resting ECG suffer an increased risk of VF, this subgroup of IVF patients has a unique clinical feature.

Effects of prostaglandin F_(2α) on small intestinal interstitial cells of Cajal

AIM：To explore the role of prostaglandin F2α（PGF2α） on pacemaker activity in interstitial cells of Cajal（ICC）from mouse small intestine. METHODS：In this study,effects of PGF2αin the cultured ICC cells were investigated with patch clamp technology combined with Ca 2＋ image analysis. RESULTS：Externally applied PGF2α（10μmol/L）produced membrane depolarization in current-clamp mode and increased tonic inward pacemaker currents in voltage-clamp mode.The application of flufenamic acid（a non-selective cation channel inhibitor）or niflumic acid（aCl channel inhibitor）abolished the generation of pacemaker currents but only flufenamic acid inhibited the PGF2α-induced tonic inward currents.In addition,the tonic inward currents induced by PGF2αwere not inhibited by intracellular application of 5’-[-thio]diphosphate trilithium salt.Pretreatment with Ca 2＋ free solution, U-73122,an active phospholipase C inhibitor,and thapsigargin,a Ca 2＋ -ATPase inhibitor in endoplasmic reticulum,abolished the generation of pacemaker currents and suppressed the PGF2α-induced tonic inward currents.However,chelerythrine or calphostin C,protein kinase C inhibitors,did not block the PGF2α-induced effects on pacemaker currents.When recording intracellular Ca 2＋ （[Ca 2＋ ]i）concentration using fluo-3/AM,PGF2α broadly increased the spontaneous[Ca 2＋ ]i oscillations. CONCLUSION：These results suggest that PGF2αcan modulate pacemaker activity of ICC by acting non-selective action channels through phospholipase C-dependent pathway via[Ca2＋]i regulation

Surgical Removal of a Giant Vegetation on Permanent Endocavitary Pacemaker Wire and Lead

PACEMAKER lead infections are rare.There are only about 0.4％-1.1％ of the patients who have been implanted permanent pacemakers suffering from serious infections which lead to endocarditis.1 Generally,removal of the infected pacemaker wire and lead,long-term anti-infection therapy,and implantation of a new pacemaker to another anatomic site are accepted approaches for these patients.

Pectoral muscular twitching： a rare manifestation of spontaneous twiddler syndrome

The twiddler syndrome is maker malfunction, in which vice in its pocket results in an uncommon cause of pace-twisting or rotating of the delead retraction or coiling and subsequent malfunction of an implanted devices such as a pacemaker, an implantable cardioverter-defibrillator （ICD）, cardiac resynchronization therapy （CRT）.

Effects of Long-term Right Ventricular Apical Pacing on Left Ventricular Remodeling and Cardiac Function

Objective: To investigate the impacts of long-term right ventricular apical pacing on the ventricular remodeling and cardiac functions of patients with high-grade and third-degree atrioventricular blockage with normal heart structures and cardiac functions. In addition, we provide many evidences for choosing an optimal electrode implantation site.Methods: Study participants included patients who were admitted for pacemaker replacements and revisited for examinations of implanted pacemakers at outpatient. Pacemakers were implanted to treat high-grade and third-degree atrioventricular blockage. At the time of pacemaker implantation, patients had normal cardiac functions and showed no serious heart diseases or cardiac dilatation. The durations from the implantation to follow-up were more than 5 years. The pacing rate was higher than 80%. Patients with a left ventricular ejection fraction (LVEF) < 50% and a left ventricular end-diastolic diameter (LVEDD) > 55 mm were excluded. Ventricular remodeling was defined as follows:increase of LVEDD by 10% and a reduction of LVEF by 25% for five years after implantation. Cardiac functions were evaluated according to New York Heart Association (NYHA) classification.Results:A total of 82 patients with a mean age of (66.97±13.19) years (range, 12 to 91 years old),among which 39 male and 43 female were enrolled in this study. The average duration between two assessments was 8.7 years (104.4 months). Before pacemaker implantation, the average left atrial diameter (LA), LVEDD and LVEF were 37.0 mm, 50.23 mm and 64.87%, respectively. After the implantation, these values were 39.39 mm (P=0.000163), 50.82 mm (P=0.177842) and 60.50% (P=0.000104), respectively. Four patients (4.87%) had ventricular remodeling with deteriorations of cardiac function, three of which had anterior wall myocardial infarction after implantation and one had type II diabetes. Clinical symptoms of heart failure were not found among the patients who did not exhibit ventricular remodeling. Conclusion: Through a long-period follow-up study, we found that long-term right ventricular apical pacing in patients with normal heart structure and cardiac function would not generally cause ventricular remodeling and clinical deteriorations of cardiac function. Right ventricular apical is a safe and effective site for pacing electrode wire implantation.

Enhancement of pacemaker induced stochastic resonance by an autapse in a scale-free neuronal network

An autapse is an unusual synapse that occurs between the axon and the soma of the same neuron. Mathematically, it can be described as a self-delayed feedback loop that is defined by a specific time-delay and the so-called autaptic coupling strength. Recently, the role and function of autapses within the nervous system has been studied extensively. Here, we extend the scope of theoretical research by investigating the effects of an autapse on the transmission of a weak localized pacemaker activity in a scale-free neuronal network. Our results reveal that by mediating the spiking activity of the pacemaker neuron, an autapse increases the propagation of its rhythm across the whole network, if only the autaptic time delay and the autaptic coupling strength are properly adjusted. We show that the autapse-induced enhancement of the transmission of pacemaker activity occurs only when the autaptic time delay is close to an integer multiple of the intrinsic oscillation time of the neurons that form the network. In particular, we demonstrate the emergence of multiple resonances involving the weak signal, the intrinsic oscillations, and the time scale that is dictated by the autapse. Interestingly, we also show that the enhancement of the pacemaker rhythm across the network is the strongest if the degree of the pacemaker neuron is lowest. This is because the dissipation of the localized rhythm is contained to the few directly linked neurons, and only afterwards, through the secondary neurons, it propagates further. If the pacemaker neuron has a high degree, then its rhythm is simply too weak to excite all the neighboring neurons, and propagation therefore fails.

Effects of external stimuli on the pacemaker function of the sinoatrial node in sodium channel gene mutations models

Loss of function and gain of function mutations of the sodium channel were investigated using an intact two-dimensional rabbit sinoatrial node (SAN) and atrial cell model. The effects of three external stimuli (acetylcholine secretion by the vagal nerve, acid-base concentration, and tissue temperature) on cardiac pacemaker function and conduction were studied. Our results show that these two groups of mutations have different effects on pacemaker function and conduction. Furthermore, we found that the negative effects of these mutations could be altered by external stimuli. The bradycardic effects of mutations were magnified by an increase in acetylcholine level. Changes in acid-base concentration and tissue temperature increased the ability of the SAN to recover its pacemaker function. The results of this study increase our understanding of sodium channel disorders, and help to advance research on the treatment of these conditions.